It has been recognized in the art for some time that to eliminate binding of piston rods in their associated cylinder barrels on multi-section telescopic crane booms some form of connection other than mere pinning of rods and/or cylinder barrels to their respective boom sections must be employed in order to maintain adequate alignment. Recently in the art floating or lost motion rod connections have been devised to improve alignment of hydraulic cylinder assemblies in relation to their associated boom sections and thus lessen the requirement for extremely close and costly manufacturing tolerances in telescopic crane booms. While such floating rod connections have successfully alleviated the alignment problem, the piston rod still was not held against possible rotation about a horizontal transverse axis and this gives rise to another problem.
It is well known that column loading capacity is greatly increased when both ends of a column have end fixity. Thus, the column loading capacity of hydraulic cylinder assemblies in multi-section telescopic booms has been limited due to the non-fixity of the floating type of rod end connection.
As a result of the above, the present invention has been devised not only to provide the necessary degree of alignment under all operating conditions between the connecting points of cylinder barrels and rods with their respective boom sections, but also to provide the required end fixity at both ends of the column formed through each hydraulic cylinder assembly of a telescopic crane boom. In this manner, the invention by increasing the column load bearing efficiency of the boom assembly renders it possible to use lighter weight cylinder assemblies, thus reducing the overall weight and cost of the boom while increasing its load lifting capacity.
Other features and advantages of the invention will become apparent during the course of the following detailed description.